This invention relates to the field of medical devices, and more particularly to a guide wire for advancing a catheter within a body lumen in a procedure such as percutaneous transluminal coronary angioplasty (PTCA).
In a typical PTCA procedure, a guiding catheter having a preformed distal tip is percutaneously introduced into a patient""s peripheral artery, e.g. femoral or brachial artery, by means of a conventional Seldinger technique and advanced therein until the distal tip of the guiding catheter is seated in the ostium of a desired coronary artery. A guide wire is first advanced by itself through the guiding catheter until the distal tip of the guide wire extends beyond the arterial location where the procedure is to be performed. Then a catheter is mounted onto the proximal portion of the guide wire which extends out of the proximal end of the guiding catheter which is outside of the patient. The catheter is advanced over the guide wire, while the position of the guide wire is fixed, until the operative element on the catheter is disposed within the arterial location where the procedure is to be performed. After the procedure is performed, the catheter may be withdrawn from the patient over the guide wire or the guide wire repositioned within the coronary anatomy for an additional procedure.
Conventional guide wires for angioplasty, stent delivery, atherectomy and other intravascular procedures usually have an elongate core member with one or more segments near the distal end thereof which taper distally to smaller cross sections. A flexible body member, such as a helical coil or a tubular body of polymeric material, is typically disposed about and secured to at least part of the distal portion of the core member. A shaping member, which may be the distal extremity of the core member or a separate shaping ribbon which is secured to the distal extremity of the core member, extends through the flexible body and is secured to the distal end of the flexible body by soldering, brazing or welding; or an adhesive may be used in the case of polymeric flexible bodies which forms a rounded distal tip. The leading tip is highly flexible and will not damage or perforate the vessel. The portion behind the distal tip is increasingly stiff, which better supports a balloon catheter or similar device.
A major requirement for guide wires is that they have sufficient column strength to be pushed through a patient""s vascular system or other body lumen without kinking. However, they must also be flexible enough to avoid damaging the blood vessel or other body lumen through which thy are advanced. Efforts have been made to improve both the strength and flexibility of guide wires to make them more suitable for their intended uses, but these two properties are for the most part diametrically opposed to one another in that an increase in one usually involves a decrease in the other.
In order to fulfill these requirements, guide wires now include two different types of material joined together with a connecting tube, hypotube, or sleeve, so that a proximal core will consist of a material having sufficient column strength and a distal core will be made of a flexible material to advance through a body lumen. Currently, an expensive nitinol hypotube or connecting tube is used to join a proximal stainless steel core to a nitinol distal core on certain types of guide wires. An example of this type of guide wire can be seen in, for example, U.S. Pat. No. 6,248,082 (Jafari).
The present invention is directed to an intravascular guide wire having at least two core materials joined together without the use of a hypotube. In one embodiment, the invention provides a core having a proximal core section with a proximal end and a distal end and a distal core section with a proximal end and a distal end. It is preferred that the proximal core section is made of stainless steel to provide sufficient column strength, and the distal core section is made of nitinol which is flexible to advance through a tortuous body lumen. The distal end of the proximal core section and the proximal end of the distal core section are formed into a complementary shapes, and then placed into a fixture in opposing directions with a small gap in-between the ends. The small gap allows for a mass of hardened material to wick therein. Once the proximal and distal core sections are bonded together, the guide wire is ground to a required outer diameter depending on the design needs of the specific guide wire.
The geometric design of the distal end of the proximal core and the proximal end of the distal core (xe2x80x9cthe connecting endsxe2x80x9d) can be constructed using a variety of methods and can be shaped in a variety of designs. The methods for forming the complementary geometric shapes into the connecting ends include, but are not limited to, grinding, milling, electrical discharge machining (EDM), laser cutting, etc. Designs of the connecting ends can include a D-shape cross-sectional shape, or a D-shape cross-sectional shape with a backside of one of the connecting ends including a taper. Another embodiment includes a D-shape cross-sectional shape with a serration, and a taper may be added to the backside of this design as well. Yet another embodiment includes a tapered D-shaped cross-sectional shape. The connecting ends may also have locking serrations, where the locking serrations of the ends mechanically grip, clasp, or engage one another. These and other complementary interfacing shapes may be used at the connecting ends.
The mass of hardened material that is used to join the proximal and distal cores may be any bonding material, including the following: solder, brazes, epoxies, glues, laser welds, spot welds, etc. that are preferable for the wire type and provide the required functional attributes. Joining the two cores together can be accomplished by dispensing, for example, solder in-between the connecting ends and/or encasing the connecting ends with solder.
The present invention method of joining a proximal and a distal core section can be applied to any two wires, and to any guide wire having a diameter ranging from about 0.006 to 0.040 inch. Wire materials that may be combined through this method include, but are not limited to, all types of metals, alloys, polymers, and composite materials.
The present invention can also be used to create a guide wire with two lap joints. One joint would connect the proximal core section to the distal core section, and the second joint would connect a shaping ribbon to the distal end of the distal core section.
These and other advantages of the invention will become more apparent from the following detailed description thereof and the accompanying exemplary drawings.